Prostanthera: Greenhouse Plants
C – cool, minimum of 7°C (45°F)
Australia and Tasmania
These are the Australian Mint Bushes and although they can almost certainly grow well in a frost free house, some even managing to survive in the mildest places outside, the early flowering species develop their flower buds during late autumn and winter which makes them vulnerable to cold weather and draughts. The plants are spotted with resin secreting glands so that as you brush past them a strong menthol smell scents the air. Prostanthera cuneata is perhaps the best known although not the most spectacular flowerer. It makes a small shrub with white, purple spotted flowers in June. P. rotundifolia is a much taller plant which makes a fine flowering bush at 2 m (6 ft) or more. Purple-blue flowers are produced in the spring. P. nivea the Snowy Mint Bush has sprays of white flowers with just a touch of lilac and grows to 1.2 m (4 ft). My favourite is P. melissifolia, the Balm Mint Bush, which is spectacular when covered with its pinky-purple flowers. These are excellent either in pots, flowering when still small, or planted in the border where they can reach their full height. Take care that they do not become too dry in winter; especially if they have produced small flower buds which may drop off. Cuttings root easily enough during summer or when non flowering material can be found. Seed is also available.